Printing press web supporting and driving rolls



July 29, 1969 H. A. DU FRESNE 3,457,657

7 PRINTING PRESS WEB SUPPORTING AND DRIVING ROLLS Filed Jan.'16, 1967 2 Sheets-Sheet 1 O C 0 1x0 0 V .41 A \4 34 W I I3 2 "My 7 V V 22 F I I3 :EI INVENTOR.

HAROLD A. DU FRESNE ATTORNEY July 29, 1969 H. A. DU FRESNE PRINTING PRESS WEB SUPPORTING AND DRIVING ROLLS Filed Jan. 16, 1967 T'II3 1 2 Sheets-Sheet 2 T'IB. EI 1- I] lN\ 'ENTOR. HAROLD A. ou mesa:

ATTORNEY United States Patent 3,457,657 PRINTING PRESS WEB SUPPORTING AND DRIVING ROLLS Harold A. Du Fresne, Green Bay Wis., assignor to FMC Corporation, San Jose, Calif., a corporation of Delaware Filed Jan. 16, 1967, Ser. No. 609,512 Int. Cl. F26b 13/04, 3/04 U.S. Cl. 34-155 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of invention This invention relates to a system for driving at least two web material supporting rolls by a jet of air so that the peripheral speed of each roll matches, or tends to match, the speed of the web.

Description of prior art Practical problems encountered in the design of web printing presses, especially in webs which must be kept free of scratches, involves height limitations, contact of the non-printed side of the web, and the elimination or minimization of surface scratches. Printing presses are designed to accept Webs made of various compositions, for example, polyethelene, cellophane, ethyelcellulose, polyester, polystyrene, etc. Each of these exemplary webs has, by virtue of its structural properties, a reasonably well defined unit elongation at a particular temperature.

After the web has traversed the impression roll it is directed to the dryer to evaporate the ink solvents. Subjection to the elevated dryer temperatures accordingly causes the web to elongate with the unit elongation increasing from the entrance to the exit of the dryer. Thus, combined with the average web speed, there is existent in the dryer section slight increases in velocity of the web due to such unit elongation. It is to be understood, of course, that the web is drawn through the press at a tension which minimizes web elongation.

In view of these considerations it is to be realized that each of the above mentioned web-types has its own characteristic unit elongation which produces incremental velocity changes at constant web running tension.

It is conventional practice to match the surface speed of the web supporting rolls with the speed of the web by mechanical drive trains such as chains and sprockets or gearing. This has proved to be expensive and not subject to the close tolerance speed adjustment required to match the speed of the successive rolls with the various unit elongations of the web types. This requirement of speed matching is necessary, as mentioned above, to prevent scratching of the web and to insure print registration.

SUMMARY OF THE INVENTION In accordance with the present invention the web guide and supporting rolls are rotatably mounted on shafts which lie transverse to the direction of web movement Patented July 29, 1969 and are longitudinally spaced a sufiicient distance apart to provide support for the web as it passes through the dryer. Since the rolls are arranged in a substantially horizontal plane, the arc of contact of each roll is very small and theoretically it may be said that the web is tangent to the rolls. Although it may be possible to increase the arc of contact by making the dryer in an arched or circular shape, printing plants do not usually have the ceiling height to permit such a construction. Consequently, due to point of contact of the web with the guide supporting rolls it is essential when matching the linear speed of the rolls with that of the web to provide a roll of eX- tremely lightweight and yet one not affected by the temperature levels in the dryer. To fulfill this requirement the present invention discloses a roll construction made of thin wall aluminum tubing. By virtue of this construction a roll of low inertial mass results which will quickly react to the accelerations and decelerations of the web so as to match the peripheral speed of the roll with the web speed.

Further and in accordance with this invention the roll supporting shaft is provided with two sets of bearings, one of which rotatably mounts the shaft on the dryer frame and the other rotatably mounting the roller on the shaft. In this way the possibility of restraining the rotation of the roller due to a sticky bearing is minimized or prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a side elevation of a typical flexographic press incorporating the present invention,

FIGURE 2 is a plan view, partly in section, of FIG- URE 1 showing some details of the dryer and the air distribution system,

FIGURE 3 is an enlarged transverse section of FIG- URE 2 taken substantially along the line 3-3,

FIGURE 4 is a further enlarged transverse section of FIGURE 3 taken substantially along the line 4-4 showing the relationship of the web with the drying jet and the supporting roll, and further showing in greater detail the air tendency drive for the supporting roll,

FIGURE 5 is an enlarged fragmentary plan view showing the manner in which the roll is supported in the drying oven,

FIGURES 6 and 7 are similar to FIGURES 4 and 5 illustrating a modification of the present invention.

The fiexographic press shown in FIGURE 1 is generally indicated by a numeral 10 and it includes upwardly extending frame members 12 and 14 on the upper ends of which is mounted a longitudinally extending oven 16. On the upper surface of the oven housing there is provided a main oven supply fan 18 arranged to draw in air through a main oven burner 20 and discharge it to a hot air supply plenum 22.

The main oven is provided with an exhaust fan 24 which removes the solvent laden air therefrom. As is conventional in the art there is also provided a between-color burner oven 26 connected to a fan 28 which discharges the heated air through a duct system 30 downwardly and laterally at circumferentially spaced areas of the impression roll 32. Also mounted above the periphery of the impression roll 32 there are a plurality of printing units 34 which impress upon the roll the desired designs and information.

A large roll of web material is carried on a conventional unwind stand 36. The web, indicated by the letter W, passes through in-feed tension rolls 38, over and under a plurality of guide rolls directing the web upwardly and under the oven 16. The web then passes over the impression roll 32 where it is imprinted by the various printing units 34. The web is then directed through the oven 16 where it encounters a plurality of guide and support rolls 3 which are the subject matter of the present invention. Above each of the rolls 40 drying jets 42 direct heated air on the printed side of the web to evaporate the ink solvents. The web then passes over a web conditioner 44 through cooling rolls 46, and is then wound on a core supported on a rewind stand 48.

In FIGURES 2 and 3 there is shown the general arrangement of the hot air distribution system for the drying jets 42 with part of the air entering a plurality of tubes which direct a jet of air to a fan or paddle wheels 52 which impart torque to the web guide and support rolls 40. As shown best in FIGURE 3, the oven 16 is generally rectangular in configuration and its lateral sides are defined by longitudinally extending channels 54 and 56 interconnected by a lower plate 58 and an upper plate 60. The main air plenum chamber 22 preferably takes the form of a rectangular conduit which is attached in any desired manner to the channel 56. The drying jets 42 have a hollow interior and a plurality of small holes 62 which extend substantially from one end of the web to the other so as to distribute heated air issuing therefrom across the entire width of the web. Each of the drying jets further includes a conduit portion 64 extending through an appropriately shaped hole formed in a channel 56 and thus establishes communication with the main air supply plenum 22.

As shown in FIGURE 2 a pivotally mounted damper 66 is arranged to control the amount of heated air which may be directed into each of the drying jets 42. An operating rod 68, projecting through the outer vertical wall of the main air supply plenum 22, can be appropriately manipulated by the operator to control the amount of air which is directed from the plenum 22 to each of the drying jets 42.

In accordance with the main feature of the invention the web guide and supporting rolls 40 are made of the lightest possible material which will operate at the maximum temperature envisioned by web printing presses of the type referred to in this specification. The rolls 4%) comprise a thin wall piece of aluminum tubing 70 which is rotatably mounted on a shaft 72. The ends of the shaft are rigidly connected by bolts 74 to the channels 54 and 56. In a manner which will be described in connection with FIGURES 4 and 5, the fan or paddle wheels 52 are carried by the aluminum shells 70 in order to impart torque thereto from the jet of air issuing from the tubes 50. The fan or paddle wheel 52 is intentionally designed to provide an inefficient conversion of dynamic fluid energy to mechanical work so that the rolls 40 will be immediately responsive to match their individual peripheral speed with the speed of the web which makes point contact therewith.

Considering FIGURES 4 and 5 together, it would be seen that the fan or paddle wheel 52 is rigidly connected by screws 76 to a tubular collar 78 fitted within the aluminum shell 70. Another collar 80 is fixed to the shaft 72 preferably by a set screw 82. A bearing 84, between these collars, rotatably mounts the shell 70 on the shaft 72. Although the mounting for one end of a guide support roll has been shown and described it is to be understood that both ends of all of the rollers are mounted in a similar manner.

The fan or paddle wheel 52 may be made in various ways such as casting, machining, or of sheet metal. The preferred form, due to its economy of manufacture, is the one made of sheet metal. By this method of manufacture a disk of thin material is sheared at circumferentially spaced points to define surfaces 86. Once sheared, that portion is bent along the radius to provide projecting paddles or fins 88 against which the high velocity air, issuing from the tubes 50, impinge to impart torque to the guide rolls 40. While it is preferred that this invention be practiced with a fan or paddle Wheel of the above described type it is to be recognized that the vanes or paddles may be formed in the collar 78 by having a portion thereof extending beyond the end of the aluminum shell 70 and forming, in any suitable manner, a plurality of regularly circumferentially spaced reaction surfaces against which the jet of air is directed. It is also possible to form reaction surfaces in the aluminum shell 70. All of these variations will result in the new and improved correlation of structure for the purpose intended.

It will be noted by inspection of FIGURE 5 that the tube 50 for directing the portion of the high velocity air from the main air supply plenum 22 to the fan or paddle wheels 52 is formed with a flared inlet 90 which assists in entraining a sufiicient mass of air to pass through the tube 50. Since the wheels 52 are mounted without being encased in a shroud and the fact that the paddles 88 are not shaped to extract the maximum amount of energy from the air impinging thereon, it is to be recognized that the torque imparted to the shell 70 is very low in value. In addition, any external forces acting on the shell 70 which are additive or in opposition to direction of the torque applied to the wheels 52, will not affect the speed relationship between the shell 70 and the web since the wheels 52 have been purposely designed to provide for a large percentage of slip. This, in conjunction with the low inertia of the rollers 40 prevents or minimizes the existance of relative velocity between the roller 40 and the web.

In FIGURES 6 and 7 there is shown a modification of the invention which is designed to reduce the possibility of a sticky bearing preventing the rotation of the rolls 40. Similar numerals in these figures will apply to parts which are identical to the preferred form shown in FIG- URES 4 and 5.

FIGURE 7 best illustrates the differences in this construction. Inspection of this figure will show that the ends of the shaft 72 are rotatably mounted in flange bearings 92 rigidly connected to the channel 56. Again it is to be appreciated that each end of all of the shafts 72 are mounted in a similar manner. As in the preferred embodiment the shell 70 is rotatably mounted on the shaft 72 by bearing 84. The fan or paddle wheel 52 however is formed with a boss 94 which is tapped so that a set screw 96 secures the fan 52 to the shaft 72. By this construction the output of the fan 52 is mainly imparted to the shaft 72 while a minimal portion, proportional to the friction of the bearing 84, is transferred to the shell 70. This coupled with the low energy conversion eificiency of the fan 52 further insures speed matching of the rollers 40 with the web speed.

Due to certain environmental conditions such as higher temperatures and dusty atmospheres, mounting of the guide rolls as shown in FIGURE 7 also reduces to an absolute minimum the possibility of a sticking guide roll because four bearings are provided for each roller. As indicated above avoidance of sticky rollers is essential to produce a printed web which is commercially acceptable.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is re garded to be the subject matter of the invention as set forth in the appended claims.

Having completed a detailed description of the invention so that those skilled in the art could practice the same, I claim:

1. In a printing press of the character described which is adaptable to print plastic webs, an oven having a drying chamber for passage therethrough of such web to evaporate the ink solvents, a hot air supply plenum, a plurality of web guiding and supporting rolls rotatable about axes which are substantially located in a common plane, such web while moving through said drying chamber makes point contact with each of said rolls, means for directing heated air from said plenum to said drying chamber shafts for each of said rollers, carried by the side walls of said drying chamber, fan wheels for each of said rollers, and means for deriving a jet of air from said plenum and directing it against each of said fan wheels to thereby impart torque to said rollers, the torque output of said fan wheels being such that the rollers are substantially immediately responsive to the speed and changes in speed of such Web as it passes through said drying chamber.

2. The invention according to claim 1 wherein said roller is made of a thin shell of heat resistent material to reduce the mass of said roller to a minimum so it is quickly responsive to speed variations of such Web.

3. The invention according to claim 1 wherein the ends of said shafts are mounted in bearings fixed to the side walls of said drying chamber.

4. The invention according to claim 1 wherein said fan wheels are mounted to rotate with said rollers.

5. The invention according to claim 3 wherein said fan wheels are rigidly connected to said shafts.

References Cited UNITED STATES PATENTS 735,790 8/ 1903 Meerza. 1,992,989 3/1935 Burns 34-155 2,151,049 3/1939 Laing 34110 XR 3,358,384 12/1967 Gustafsson et a1. 34155 XR FOREIGN PATENTS 491,173 3/1953 Canada.

FREDERICK L. MATTESON, JR., Primary Examiner 15 H. B. RAMEY, Assistant Examiner 

